The Scottish politician, who told the BBC on Friday "you can't get more gay than me", blasted same sex marriage as "bollocks", claimed it caused homophobia, and said of Ukip's exclusion from the Pride parade: "I've never heard so much twaddle in all my life".
Coburn's comments came in a debate with veteran human right campaigner Peter Tatchell over the decision taken in June by Pride organisers to exclude Ukip members on health and safety grounds.
Coburn is Scotland's single Ukip MEP
On the accusations, Coburn said: "I've never heard so much twaddle in all my life. Typical Mr Tatchell. Well I'm gay, and you can't get more gay than me - and I'm the leader of Ukip Scotland."
Defending his party, the Ukip MEP said: "We have people in our party who've said stupid things in the same way that people in every other party say stupid things.
"The trouble is that when we say it everybody makes a fuss about it. We are not a right wing party, we are a libertarian party."
While Coburn said he would not be able to attend the demonstration personally, he told the BBC's Daily Politics he believed many party members and supporters would still turn up on the day on the sidelines.
"As far as I'm concerned our people are probably going to turn up at the sidelines," he said.
Peter Tatchell hit back, defending Ukip's Pride ban, claiming that the party's record on sexual equality meant it was not "appropriate" for members to attend.
Tatchell pictured in Belfast about to deliver the Amnesty International Pride Lecture as part of the city's gay pride festival
He likened the case to a situation in which the annual London Notting Hill Carnival - originally a festival for Afro-Caribbean communities to celebrate their own cultures and traditions - banned British National Party supporters from attending; a justifiable argument he said.
Tatchell also decried Ukip for not supporting same sex marriage, saying their manifesto offered no gay rights policies.
"They don't support gay rights. At the last election, they did not have a single gay rights policy.
"Instead, they proposed weakening equalities laws to allow religious people to discriminate against us.
"So if they support discrimination, what right have they got to march in a parade that's against discrimination?"
The frosty frenzy came just hours before the Supreme Court in America ruled that same-sex marriage was a legal right across all of the United States by a 5-4 majority.